Continuous single-pile sheet deliveries have been known for some time. They consist generally of a main pile support, and an auxiliary support which is moved into position above a full pile on the main support to temporarily receive sheets from a sheet conveyor while the full pile is being removed from the delivery. Such a system is shown in Neri U.S. Pat. No. 2,699,943. An empty new skid is placed on the main support and is brought closely adjacent the bottom of the auxiliary support. The latter is then withdrawn to deposit sheets on the empty new skid thus enabling delivery of sheets to continue uninterrupted.
"Racking" systems, an example of which is illustrated in Rooney U.S. Pat. No. 2,663,357, have also been known for some time. A principal function of such a racking system is to enable the delivery of sheets in small piles, between which are inserted plywood boards. These boards are normally provided with corner-supporting blocks which raise each board slightly above the small sheet pile therebeneath. This not only assists in ink drying, but further reduces offsetting of fresh ink from one sheet against the next by reducing the height and thus the weight of each pile.
Double-delivery systems such as that shown in Niles et al U.S. Pat. No. 2,673,735 enable delivery of sheets to one or the other of a pair of piles. In addition, sheets may be alternately delivered to both. Double-deliveries permit ununinterrupted delivery of sheets, since a full pile can be removed from one pile location while sheets are temporarily delivered to the other. It is not uncommon to find that one of the two deliveries is provided with a racking device to enable accomplishment of the previously-described racking. An example of this general type of system is illustrated in Koch U.S. Pat. No. 3,477,710. While the Koch system does not have a true double delivery, it functions as one by diverting sheets to an alternate pile location during racking.